Circuit and method for controlling light-emitting components

ABSTRACT

Circuit arrangement or circuit, in particular driver circuit, and a method for controlling at least one light-emitting component, such as an electro-optical transducer, a light-emitting diode (LED), an electroluminescent diode, a laser, or a semiconductor laser, by switching a switching element between a first switching position and a second switching position, and the voltage supply is effected by a supply element, such as a voltage source or a current source supported by a decoupling capacitor on the output side, so that current drain and output resistance are as low as possible, so that the highest possible frequency or switching speed as well as the highest possible output voltage for the light-emitting component can be achieved, the light-emitting component is controlled by varying its operating voltage, in particular by switching between the switching positions, and the first and second switching positions are of low impedance for the operating frequency.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 12/654,515,filed Dec. 22, 2009, now U.S. Pat. No. 8,855,154, issued Oct. 7, 2014,which application no. 12/654,515, is a continuation of application no.PCT/EP2008/057785, filed Jun. 19, 2008, which application no.PCT/EP2008/057785 claims the priority of German application no. 10 2007028 576.2, filed Jun. 19, 2007, and which application no.PCT/EP2008/057785 claims the priority of German application no. 10 2007040 151.7, filed Aug. 24, 2007, and which application no.PCT/EP2008/057785 claims the priority of German application no. 10 2008001 453.2, filed Apr. 29, 2008, and each of which is incorporated hereinby reference.

FIELD OF THE INVENTION

The present invention relates generally to the technical field ofcontrolling light-emitting components.

The present invention relates more specifically to a circuit arrangementor circuit, in particular a driver circuit, according to the preamble ofclaim 1 and a method for controlling at least one light-emittingcomponent according to the preamble of claim 11.

Within the scope of the present invention, the term light orlight-emitting is understood not only as the range of electromagneticradiation visible to the eye, extending in a wavelength range from about380 nanometers to about 780 nanometers (which corresponds to a frequencyof about 789 terahertz down to about 385 terahertz).

Rather, the term light or light-emitting is understood as the entireelectromagnetic wavelength or frequency spectrum, including the spectrumnot visible to the eye, in particular the I[nfra]R[ed] range (wavelengthrange up to about 2,000 nanometers or frequency range down to about 150terahertz), for example a wavelength of about 850 nanometers or afrequency of about 350 terahertz.

BACKGROUND OF THE INVENTION

Exemplary circuit arrangements known from the PRIOR ART for controllinga light-emitting component E for the purposes of data transmission fromthe light-emitting component E (=so-called source) to a light-receivingcomponent (=so-called sink) are shown in FIG. 5A to FIG. 5C.

Typically, a semiconductor laser or an electroluminescent diode is usedas light-emitting component E, in particular as an optical transmittingelement or as an optical source, for optical data transmission.

This semiconductor laser or this electroluminescent diode is, accordingto the prior art, for example supplied by an electronic driver circuitS1 (cf. FIG. 5 a), S2 (cf. FIG. 5B) or S3 (cf. FIG. 5C) with thenecessary operating voltage, the bias current and the modulation currentfor correct operation.

The driver circuit S1, S2, S3 can be constructed both as an integratedcircuit (or IC=Integrated Circuit) and also discretely from individualcomponents on a printed circuit board (or PCB=Printed Circuit Board).

In the example from the prior art shown in FIG. 5A, the light-emittingcomponent E can be powered via a first current path I₁ and additionallyvia a second current path I₂. For this purpose in the first current paththe current I₁ flows from a DC voltage source Q via the light-emittingcomponent E to a constant current source K1 for I₁.

By switching to active or switching on the second current path I₂ bymeans of a switch U which controls the current level of thelight-emitting component E, the entire current I_(ges)=I₁+I₂ flowsthrough the light-emitting component E, otherwise the current I₁. Aconstant current source K2 is provided for the power supply of thesecond current path I₂.

The modulation of the light-emitting component E is thus effected in theform of current adjustment or current modulation, that is by temporallyvarying the current intensities flowing through the light-emittingcomponent E between the values I₁ and I₁+I₂.

The arrangement of switch U and dummy load R has the effect that at theswitch U the same current always flows in relation to the node pointassigned to the second current path I₂, wherein when the second currentpath I₂ is not switched to the light-emitting component E, the currentI₂ in the dummy load R is substantially converted into thermal energywhich can, for example, be up to about fifty percent of the operatingtime of the light-emitting component; however, the current I₂ isdisadvantageously also present when this current I₂ is no longer needed.

Furthermore, in the example from the prior art shown in FIG. 5A, the twoconstant current sources K1 and K2 are arranged in the high-frequencypath which necessarily involves parasitic capacitances. Also in theexample from the prior art shown in FIG. 5A, an undesirable high voltagedrop or a high saturation voltage necessarily occur.

In the second exemplary driver circuit S2 according to the prior artshown in FIG. 5B, when the second current path I₂ is switched to activeor switched on, the current I₁+I₂ flows through the light-emittingcomponent E by means of the switch U which controls the current level,otherwise the current I₁; however, the current I₂ is disadvantageouslyalso present when this current I₂ is no longer needed.

The operating voltage of the light-emitting component E depends on thesupply voltage supplied by the voltage source Q (=for example aboutthree volts) and on the constant current source K1 or on the constantcurrent sources K1, K2.

In the third exemplary driver circuit S3 according to the prior artshown in FIG. 5C, either the current I₁+0.5I₂ or the current I₁−0.5I₂,which results in a current difference of I₂, flows through thelight-emitting component E depending on the position of the switch Uwhich controls the current level.

The arrangement of a (not obligatory) inductor L at which, for example,a voltage loss of about 0.5 volt occurs, is usually used to increase theimpedance of the constant current source K1 at high frequencies andconsequently makes it possible to use a constant current source K1 whichdoes not have a high output impedance at high frequencies.

In addition to the previously described driver circuit S3, a drivercircuit with inductor is also known from the prior art document U.S.Pat. No. 6,667,661 B1.

In the electronic driver circuit S3 shown in FIG. 5C, it isdisadvantageously necessary to provide external components, that is,disposed outside the integrated circuit, such as a capacitor C.

As a result of the arrangement of inductor L and capacitor C,undesirable electromagnetic interference effects such as electromagneticoscillations can furthermore occur. In this connection, for example, theprior art document U.S. Pat. No. 7,133,429 B2 is concerned with theproblem of avoiding electromagnetic oscillations of a laser drivercircuit with signal-amplified data transmission.

Another disadvantage of conventional circuit arrangements is their highvoltage drop across the components in series with the light-emittingcomponent. Particularly for applications in which only a small supplyvoltage is available, this conflicts with the aim of providing thehighest possible operating voltage at the light-emitting component.

The technical formulation of the problem of providing a driver circuitfor optical data transmission with low power drain is known, forexample, from the prior art documents U.S. Pat. No. 6,965,722 B1 andU.S. Pat. No. 7,154,923 B2. However, the structure of the drivercircuits described in these documents is very complex.

In addition, circuit arrangements known from the prior artdisadvantageously have high output resistances (=real parts of theoutput impedances). This limits the speed, in particular for thetransient ringing (or settling) or the circuit arrangement since themaximum switching frequency f behaves substantially reciprocallyproportional to the product of the total capacitance C and totalresistance R at the output of the controlling or driver circuit, wherein

the total capacitance C, for example, is substantially dominated by theparasitic capacitive effect of the light-emitting component and

the total resistance R is substantially given by the parallel circuit ofthe output resistance of the driver circuit and the input resistance ofthe light-emitting component.

Finally, another technical problem of conventional circuit arrangementsis a (too) low output voltage at the light-emitting component since theconstant current source(s) require(s) a voltage (drop) of, for example,about 0.5 volt (a small voltage drop in the order of, for example, about0.2 volt also occurs at the voltage source providing the supply voltageas long as this is a regulated voltage source).

Another small voltage drop in the order of, for example, about 0.1 voltoccurs at the switching element U so that (too) little voltage occursacross the light-emitting component and therefore (too) little voltageis available at the light-emitting component.

OBJECTS AND SUMMARY OF THE INVENTION

Starting from the previously outlined disadvantages and inadequacies andacknowledging the outlined prior art, it is the object of the presentinvention to further develop a circuit arrangement of the type specifiedinitially and a method of the type specified initially so that thepreviously outlined disadvantages and inadequacies are avoided; inparticular current drain and output resistance should be as low aspossible so that the highest possible frequency or switching speed aswell as the highest possible output voltage for the light-emittingcomponent can be achieved.

This object is achieved by a circuit arrangement having the featuresspecified in claim 1 and by a method having the features specified inclaim 11.

The light-emitting component is

-   -   supplied with a first operating voltage in the first switching        position of the switching element,    -   supplied with a second operating voltage in the second switching        position of the switching element and    -   controlled by switching between the first operating voltage and        the second operating voltage; in particular the light-emitting        element is controlled by switching between the switching        positions of which at least the first switching position of the        switching element and the second switching position of the        switching element are of low impedance for the operating        frequency.

The switching element is expediently configured as at least one closingswitch or at least one reversing switch or as at least one changeoverswitch, for example, as at least one switching transistor such as forexample as at least oneM[etal]O[xide]S[emiconductor]F[ield]E[ffect]T[ransistor]. In this way,at least two operating states of the circuit arrangement with lowimpedances in each case, in particular without further current losses,can be achieved.

A supply element in the sense of the present invention can, for example,be achieved as at least one voltage source or as a combination ofcurrent source and decoupling capacitor so that a low output impedanceis produced for the relevant operating frequencies.

The light-emitting component can thus be controlled by varying itsoperating voltage by means of switching the voltage the light-emittingelement is supplied with, in particular the voltage entering into thelight-emitting component, and can, for example, be used for optical datatransmission. For this purpose, the light-emitting component convertselectrical signals into optical signals which are coupled into anoptical waveguide, for example, into a glass fiber or into a plasticfiber.

In the present invention, the light-emitting component is thereforevoltage-driven in at least two operating points which can be configuredby means of the switching element and optionally by means of at leastone control device, in particular signal source, for controlling theswitching element.

The circuit arrangement according to the invention is particularlyadvantageous on account of its low power drain. The power drain isparticularly low because, unlike the prior art, there is no othercurrent path outside the light-emitting component.

Furthermore, in the present invention the person skilled in the art willparticularly appreciate the comparatively high output voltage availablefor the light-emitting component.

Furthermore, the low output impedance is a further advantage of thepresent invention. This makes it possible to achieve a high speed,particularly for the settling of the circuit arrangement since themaximum switching frequency f behaves substantially reciprocallyproportional to the product of the total capacitance C and totalresistance R at the output of the controlling or driver circuit, wherein

-   -   the total capacitance C, for example, is substantially dominated        by the parasitic capacitive effect of the light-emitting        component and    -   the total resistance R is substantially given by the parallel        circuit of the output resistance of the driver circuit and the        input resistance of the light-emitting component.

The light-emitting component can in particular be an electro-opticaltransducer, for example a light-emitting diode(=L[ight]E[mitting]D[iode]), such as an electroluminescent diode, or alaser (=Light Amplification by Stimulated Emission of Radiation), suchas a semiconductor laser.

The controlling of the light-emitting component is effected, forexample, for the purposes of data transmission from at least onelight-emitting component (=so-called source) to at least onelight-receiving component (=so-called sink).

The data transmission can take place, for example, via at least onecarrier medium such as via glass fibers or via plastic fibers or alsovia air as carrier medium or through vacuum.

The present invention finally relates to the use of at least one circuitarrangement, in particular of at least one driver circuit, according tothe type presented hereinbefore and/or of a method according to the typepresented hereinbefore

-   -   in at least one, in particular mobile, telecommunication system,        for example in at least one communication device, such as in at        least one mobile telephone,    -   in at least one, in particular mobile, data communication system        or in at least one, in particular mobile, data processing        device, for example in at least one handheld, in at least one        notebook or in at least one P[ersonal]D[igital]A[ssistant],    -   in at least one, in particular mobile, data recording and/or        reproducing device, for example in at least one camcorder, in at        least one digital camera or in at least one        H[igh]D[efinition]T[ele]V[ision] or    -   in at least one transportation means, for example in at least        one driver assistance system or in at least one navigation        system of an automobile.

In a mobile communication device or in a mobile data processing device,the present invention can be used particularly advantageously since inthese areas of application, the supply voltage provided by the batteryor by the rechargeable battery unit, in everyday language accumulator,is limited; in the sense of the longest possible operating time of therechargeable battery, the efficient dealing with the supply voltage andthe power uptake made possible by the present invention is of particularbenefit.

As a result, by controlling the light-emitting component by means ofswitching its operating voltage, that is by the present voltage-drivenapproach according to the present invention, a very low output impedanceand therefore a very high frequency or switching speed can be achieved.

The person skilled in the art in the technical field of controllinglight-emitting components will particularly appreciate that the circuitarrangement according to the present invention and also the methodaccording to the present invention have both a low output impedance anda low energy drain.

As has already been discussed hereinbefore, there are variouspossibilities for configuring and further developing the teaching of thepresent invention in an advantageous manner. For this purpose, on theone hand reference is made to the claims subordinated to claim 1 andclaim 11 and other the hand, further embodiments, features andadvantages of the present invention are explained in detail hereinafterinter alia with reference to the exemplary embodiments illustrated byFIG. 1 to FIG. 4C.

BRIEF DESCRIPTION OF THE DRAWINGS

It is shown in:

FIG. 1 in a schematic diagram a first exemplary embodiment of a circuitarrangement according to the present invention operating according tothe method of the present invention;

FIG. 2 in a schematic diagram a second exemplary embodiment of a circuitarrangement according to the present invention operating according tothe method of the present invention;

FIG. 3 in a schematic diagram a third exemplary embodiment of a circuitarrangement according to the present invention operating according tothe method of the present invention;

FIG. 4A in a schematic diagram a fourth exemplary embodiment of acircuit arrangement according to the present invention operatingaccording to the method of the present invention;

FIG. 4B in a diagrammatic view the drain current characteristic plottedversus the gate source voltage for the transistor contained in thecircuit arrangement from FIG. 4A;

FIG. 4C in a schematic detail view a variant of the circuit arrangementfrom FIG. 4A comprising two transistors;

FIG. 5A in a schematic diagram a first exemplary embodiment of a circuitarrangement according to the PRIOR ART;

FIG. 5B in a schematic diagram a second exemplary embodiment of acircuit arrangement according to the PRIOR ART; and

FIG. 5C in a schematic diagram a third exemplary embodiment of a circuitarrangement according to the PRIOR ART.

DETAILED DESCRIPTION OF THE INVENTION

The same or similar embodiments, elements or features are provided withidentical reference numerals in FIG. 1 to FIG. 5C.

In order to avoid superfluous repetitions, the following explanationsregarding the embodiments, features and advantages of the presentinvention—unless specified otherwise—relate

-   -   both to the first exemplary embodiment of a circuit arrangement        100 shown in FIG. 1    -   also to the second exemplary embodiment of a circuit arrangement        100′ shown in FIG. 2    -   also to the third exemplary embodiment of a circuit arrangement        100″ shown in FIG. 3 and    -   also to the fourth exemplary embodiment of a circuit arrangement        100′″ shown in FIG. 4A, in FIG. 4B and in FIG. 4C.

In the first exemplary embodiment (basic concept) of the presentinvention illustrated by reference to FIG. 1, a circuit arrangement 100is shown, i.e. a controlling circuit or driver circuit, for controllinga light-emitting component 20, for example a light-emitting diode(=L[ight]E[mitting]D[iode]) or electroluminescent diode or a laser, forexample a semiconductor laser.

In addition to the light-emitting component 20, the circuit 100comprises two supply elements in the form of voltage sources or 10′(rechargeable battery unit) operated towards a reference potential W, inparticular towards earth potential or ground potential or zeropotential, for the supply of the circuit arrangement 100 with a firstoperating voltage U₁ or with a second operating voltage U.

As shown in FIG. 1, the circuit arrangement 100 is further assigned aswitching element 30, in particular a reversing switch or changeoverswitch, for example, for each switching position a switching transistorsuch as a M[etal]O[xide]S[emiconductor]F[ield]E[ffect]T[ransistor] ineach case.

This switching element 30 is configured for controlling thelight-emitting component 20 by means of switching at least between afirst switching position and a second switching position.

In this case, in the first switching position of the switching element30, the entire or almost the entire voltage U₁ provided by the firstvoltage source 10 drops across the light-emitting component 20; as anexample, in the first switching position of the switching element 30 atleast about ninety percent, for example about 99 percent, of the voltageprovided by the first voltage source 10 can drop across thelight-emitting component 20.

On the other hand, in the second switching position of the switchingelement 30, the entire or almost the entire voltage U₂ provided by thesecond voltage source 10′ drops across the light-emitting component 20;as an example, in the second switching position of the switching element30 at least about ninety percent, for example about 99 percent, of thevoltage provided by the second voltage source 10′ can drop across thelight-emitting component 20.

The circuit arrangement 100′ according to the second exemplaryembodiment of the present invention illustrated by reference to FIG. 2comprises two current sources 10 or 10′ connected in parallel to oneanother as supply elements, their outputs each being supported by acapacitor by means of a decoupling capacitor 12 or 12′.

For supplying the supply voltage 14 (so-called Thévenin voltage), forexample of the order of magnitude of about three volts, the circuitarrangement 100′ comprises a supply element in the form of a battery.

As shown in FIG. 2, the supply element can be configured as a currentsource supported by a decoupling capacitor on the output side, possiblyas a combination or interconnection of current sources 10, 10′ optimizedfor applications at low frequencies and decoupling capacitor 12, 12′.

In this case, the current source 10 or 10′ is used for tracking thecurrent as required. The decoupling capacitor 12 or 12′ is used forreducing the impedance of the node N or N′ for the range of switchingand operating frequencies of the driver circuit 100′.

Since an increase in the capacitance at the node point N or N′advantageously acts on the decoupling effect at this node point N or N′,no upper limit for its parasitic output capacitance is to be noted whendimensioning the current source 10 or 10′ since the embodiment accordingto FIG. 2 is insensitive to parasitic capacitances.

As a result, the current source 10 or 10′ can be dimensioned such thatit operates as prescribed even with a very small voltage differencebetween the supply voltage 14 and the voltage at the node point N or N′.

In the first switching position of the switching element 30, thelight-emitting component 20 is connected to the node point N at which anexemplary voltage of about 2.8 volt is applied. In the second switchingposition of the switching element 30, the light-emitting component 20 isconnected to the node point N′ at which an exemplary voltage of about2.3 volt is applied.

In this case, the node point N or N′ connecting the output of thecurrent source 10 or 10′ and the first or second switching position ofthe switching element 30 is supported by the decoupling capacitor 12 or12′ in a high-capacitance manner and substantially “not moved” with thesignal to be transmitted, that is it is constant.

Taking into account an exemplary voltage loss at the switching element30 in the order of, for example, 0.1 volt, high-frequency signalsalternating between about 2.7 volt and about 2.2 volt are in this waypossible at the light-emitting component 20 since a delimitation orseparation between the low-frequency branch of the current source 10,10′ and the high-frequency branch of the light-emitting component 20 isbrought about “on both sides” by the capacitive support of the node N orN′.

This advantageously has the effect that the low-capacitance andsmall-area reversing switch 30 makes effectively no capacitivecontribution and makes possible a high-frequency, i.e. very fast,switching between the two substantially static states.

As a result, the circuit arrangement 100′ according to the secondexemplary embodiment illustrated by reference to FIG. 2 allowsparticularly effective use of the supply voltage 14 and the possibilityof modification for the current intensities 0.5I₁ or 0.5I₂ provided bythe current sources 10 or 10′ (-->switching between the currentintensity I₁ at the light-emitting component 20 in the first switchingposition and the current intensity I₂ at the light-emitting component 20in the second switching position insofar as an activation of bothswitching positions uniformly distributed over the time average exists).

In the driver circuit 100′ the output impedance can also be kept verylow at high frequencies since this output impedance is merely limited bythe parasitic resistance of the switching element 30 so that a very highoperating frequency or switching speed can be achieved.

In the particular case of the present invention, a very high outputvoltage can be achieved for the light-emitting component 20 since only avery small voltage drop occurs via the switch 30; in addition, thecurrent source 10, 10′ is advantageously disposed in the supply path andnot in the high-frequency signal path.

In the circuit arrangement 100″ according to the third exemplaryembodiment of the present invention illustrated by reference to FIG. 3,a diode 30′ polarized in the forward direction, in particular towardsthe second switching position of the switching element 30, for example,a pn diode or a Schottky diode, is switched between the second nodepoint N′ and the second switching position of the switching element 30.This diode 30′ conducts in the forward direction, that is toward theswitching element 30, and blocks in the rearward direction.

By using such a diode 30′ switched between the node N′ and the input ofthe light-emitting component 20 as the second component of the switchingelement 30, a simplification of the same is achieved insofar as only oneswitching element is controlled and consequently only one control signalexists.

In this case, the diode 30′ takes over the function of the second (inFIG. 3 right-hand) switching position, i.e. to conduct when the first(in FIG. 3 left-hand) current path of the switch 30 is switched off.

Any possibly non-negligible forward bias of the diode 30′ polarized inthe forward direction, for example, in the order of magnitude of about0.2 volt in the case of a Schottky diode, leads to a correspondinglyhigh voltage loss between the voltage at the node point N′ and theoperating voltage available to the light-emitting component 20.

However, since this voltage loss only occurs in that switching positionwhich is intentionally assigned a reduced operating voltage at thelight-emitting component 20, the voltage loss can be compensated byraising the voltage at the node point N.

In the circuit arrangement 100′″ according to the fourth exemplaryembodiment of the present invention illustrated by reference to FIG. 4A,an n-channel M[etal]O[xide]S[emiconductor]F[ield]E[ffect]T[ransistor]30′ is switched between the second node point N′ and the secondswitching position of the switching element 30,

-   -   having its drain connection D′ connected to the second node        point N′,    -   its gate connection G′ connected to a supporting supply element        34, in particular to a supporting voltage source (for example,        about 2.8 volt) and    -   its source connection S′ connected to the input connection of        the light-emitting component 20.

In FIG. 4B the characteristic for the drain current I_(D′) of thisn-channel MOSFET 30′ is plotted versus the gate source voltage U_(G′S′)of this n-channel MOSFET 30′ (=voltage measured from gate G′ of then-channel MOSFET 30′ to source S′ of the re-channel MOSFET 30′), whereinthe current intensity I₂ assigned to the second switching positionappears with an exemplary order of magnitude of about one milliampere ata gate source voltage U_(G′S′) of, for example, about 0.6 volt.

In an alternative embodiment of the circuit arrangement 100′″ accordingto the present invention illustrated by reference to FIG. 4C, theswitching element is configured as two n-channelM[etal]O[xide]S[emiconductor]F[ield]E[ffect]T[ransistor]s 30 or 30′,

-   -   the respective drain connections D or D′ being connected via the        node N or N′ to the first current source 10 or to the second        current source 10′,    -   the gate connection G being connected to a control device 40,        for example, in the form of a signal source or its gate        connection G′, via an optional resistance element 50 to a        supporting supply element 34 or to a supporting voltage source        34 and    -   the respective source connections S or S′ being connected to one        another and to the input connection of the light-emitting        component 20.

In this case, in the variant of the circuit arrangement 100′″ accordingto the present invention illustrated by reference to FIG. 4C, aregulating/processing element 22 in the form of a comparator or in theform of an amplifier is provided,

-   -   its first input connection being connected to the second        capacitively decoupled current source 10′,    -   its optional second input connection being connected to an        optional reference voltage source 26 and    -   its output connection being connected to the supporting supply        element 34.

Although not explicitly shown in FIG. 4A, such a regulating/processingelement 22 can also be provided in the circuit arrangement 100′″according to the fourth exemplary embodiment of the present inventionillustrated by reference to FIG. 4A.

The comparator or amplifier 22 is configured

-   -   to determine the voltage present at the node point N′,    -   to compare the determined voltage with the reference voltage        Vref provided by the reference voltage source 26 and    -   if necessary, to adjust or control the voltage of the supporting        supply element 34, in particular to raise or lower this in such        a manner that the voltage at the node point N′ approaches the        value of the reference voltage Vref.

In principle, the present invention can be configured in numerous ways;in particular, by adding additional components or additional elements inthe signal and regulating paths, the present invention can be adapted tospecific requirements.

As an example, attention may be drawn to the optional resistance element50 in FIG. 4C which can be used for connecting the supporting supplyelement 34 to the gate connection G′ of the transistor 30′ in order tovary the ratio of gradients of the falling signal slope to the risingsignal slope by inductive “peaking”.

In this connection, attention may also be drawn to the fact that theterm “connection” within the scope of the present invention alsocomprises connections or types of connection which are made byadditionally inserted components or elements.

While this invention has been described as having a preferred design, itis understood that it is capable of further modifications, and usesand/or adaptations of the invention and following in general theprinciple of the invention and including such departures from thepresent disclosure as come within the known or customary practice in theart to which the invention pertains, and as may be applied to thecentral features hereinbefore set forth, and fall within the scope ofthe invention.

LIST OF REFERENCE NUMERALS

-   100 circuit arrangement, in particular control circuit or driver    circuit    -   (=first exemplary embodiment of the present invention; cf. FIG.        1)-   100′ circuit arrangement, in particular control circuit or driver    circuit    -   (=second exemplary embodiment of the present invention; cf. FIG.        2)-   100″ circuit arrangement, in particular control circuit or driver    circuit    -   (=third exemplary embodiment of the present invention; cf. FIG.        3)-   100′″ circuit arrangement, in particular control circuit or driver    circuit    -   (=fourth exemplary embodiment of the present invention; cf. FIG.        4)-   10 first supply element, in particular first voltage source, for    example first rechargeable battery unit, for supplying the circuit    arrangement 100, 100′, 100″ 100′″ with voltage, in particular with    direct voltage-   10′ second supply element, in particular second voltage source, for    example second rechargeable battery unit, for supplying the circuit    arrangement 100, 100′, 100″, 100′″ with voltage, in particular with    direct voltage-   12 decoupling capacitor, in particular capacitive support, of the    first supply element 10-   12′ decoupling capacitor, in particular capacitive support, of the    second supply element 10′-   14 supply voltage, in particular Thévenin voltage, of the supply    element 10, 10′-   20 light-emitting component, in particular electro-optical    transducer, for example light-emitting diode    (=L[ight]E[mitting]D[iode]) or electroluminescent diode or laser,    such as semiconductor laser-   22 regulating and/or processing element, in particular comparator    and/or amplifier, for example operation amplifier-   26 reference voltage source-   30 switching element, in particular closing switch or reversing    switch or changeover switch, for example switching transistor, such    as a M[etal]O[xide]S[emiconductor]F[ield]E[ffect]T[ransistor] or MOS    transistor, for example n-channel F[ield]E[ffect]T[ransistor]-   30′ second component of the switching element 30, in particular    diode polarized in the forward direction, in particular towards the    switching element, for example pn diode or Schottky diode and/or    switching transistor, such as    M[etal]O[xide]S[emiconductor]F[ield]E[ffect]T[ransistor] or MOS    transistor, for example n-channel F[ield]E[ffect]T[ransistor]-   34 supporting supply element, in particular supporting voltage    source, for the transistor 30′-   40 control device, in particular signal source, of the transistor 30-   50 resistance, in particular Ohmic resistance element-   C capacitor    -   (=third example from the prior art; cf. FIG. 5C)-   D drain connection of the transistor 30-   D′ drain connection of the transistor 30′-   E light-emitting component, in particular electro-optical    transducer, for example light-emitting diode    (=L[ight]E[mitting]D[iode]) or electroluminescent diode or laser,    such as semiconductor laser    -   (=examples from the prior art; cf. FIG. 5A, FIG. 5B, FIG. 5C)-   G gate connection of the transistor 30-   G′ gate connection of the transistor 30′-   K1 further circuit component, i.e. constant current source for I₁    -   (=examples from the prior art; cf. FIG. 5A, FIG. 5B, FIG. 5C)-   K2 second further circuit component, i.e. constant current source    for I₂    -   (=examples from the prior art; cf. FIG. 5A, FIG. 5B, FIG. 5C)-   K2′ third further circuit component, i.e. constant current source    for I₂/2    -   (=third example from the prior art; cf. FIG. 5C)-   L inductor (=third example from the prior art; cf. FIG. 5C)-   N first, in particular low-resistance node or node point between    first supply element 10, first decoupling capacitor 12 and first    switching position of the switching element 30-   N′ second, in particular low-resistance node or node point between    first supply element 10, first decoupling capacitor 12 and first    switching position of the switching element 30-   Q voltage source, in particular rechargeable battery unit or    accumulator    -   (=examples from the prior art; cf. FIG. 5A, FIG. 5B, FIG. 5C)-   R dummy load    -   (=first example from the prior art; cf. FIG. 5A)-   S source connection of the transistor 30-   S′ source connection of the transistor 30′-   S1 circuit arrangement    -   (=first example from the prior art; cf. FIG. 5A)-   S2 circuit arrangement    -   (=second example from the prior art; cf. FIG. 5B)-   S3 circuit arrangement    -   (=third example from the prior art; cf. FIG. 5C)-   T control device, in particular signal source, for controlling (the    switching of) the switching element U, in particular closing switch    control or reversing switch control or changeover switch control    -   (=examples from the prior art; cf. FIG. 5A, FIG. 5B, FIG. 5C)-   U switching element, in particular closing switch or reversing    switch or changeover switch    -   (=examples from the prior art; cf. FIG. 5A, FIG. 5B, FIG. 5C)-   Vref reference voltage provided by reference voltage source 26 or    reference voltage provided by reference voltage source 26-   W reference potential, in particular earth potential or ground    potential or zero potential

What is claimed is:
 1. A circuit for controlling at least onelight-emitting component, comprising: a) at least one supply elementprovided for supplying the circuit with voltage; b) at least oneswitching element provided, and being switchable at least between afirst switching position and a second switching position; and c) thelight-emitting component: i) can be supplied with a first operatingvoltage in the first switching position of the switching element; ii)can be supplied with a second operating voltage in the second switchingposition of the switching element; and iii) can be controlled byswitching between the first operating voltage and the second operatingvoltage.
 2. The circuit according to claim 1, wherein: a) thelight-emitting component is configured as at least one electro-opticaltransducer, in particular as at least one light-emitting diode(=L[ight]E[mitting]D[iode]) or electroluminescent diode or as at leastone laser, such as at least one semiconductor laser.
 3. The circuitaccording to claim 1, wherein: a) the supply element is configured as:i) at least one voltage source; or ii) at least one current sourcesupported by a decoupling capacitor on the output side.
 4. The circuitaccording to claim 1, wherein: a) the supply element includes at leasttwo supply elements each configured as a voltage source, and: i) in thefirst switching position almost the entire voltage provided by the firstvoltage source drops as first operating voltage at the light-emittingcomponent; and ii) in the second switching position almost the entirevoltage provided by the second voltage source drops as second operatingvoltage at the light-emitting component.
 5. The circuit according toclaim 1, wherein: a) the supply element includes at least two supplyelements which are connected to one another in parallel, each configuredas a current source supported by a decoupling capacitor on the outputside, in particular by at least one decoupling capacitor, which areconnected to at least one supply voltage, in particular to at least oneThévenin voltage.
 6. The circuit according to claim 1, wherein: a) atleast one diode polarized in the forward direction, in particulartowards the switching element, for example at least one pn diode or atleast one Schottky diode, is connected between at least one of thesupply elements and the switching element.
 7. The circuit according toclaim 1, wherein: a) a transistor is connected between at least one ofthe supply elements and the switching element; b) the drain connectionof said transistor being connected to the first supply element or to thesecond supply element; c) the gate connection of said transistor beingconnected to at least one supporting supply element, in particular to atleast one supporting voltage source; and d) the source connection ofsaid transistor being connected to the input connection of thelight-emitting component.
 8. The circuit according to claim 1, wherein:a) the switching element is configured as at least two transistors; b)the respective drain connection of said transistors being connected tothe first supply element or to the second supply element; c) the gateconnection of said transistors being connected to at least one controldevice, in particular to at least one signal source or its gateconnection, in particular via at least one resistance element, to atleast one supporting supply element, in particular to at least onesupporting voltage source; and d) the respective source connections ofsaid transistor being connected to one another and to the inputconnection of the light-emitting component.
 9. The circuit according toclaim 7, wherein: a) the transistor or the transistors is or areconfigured as at least one or twoM[etal]O[xide]S[emiconductor]F[ield]E[ffect]T[ransistor](s) or as atleast one or two MOS transistor(s), in particular as at least one or twon-channel F[ield]E[ffect]T[ransistor](s).
 10. The circuit according toclaim 6, wherein: a) at least one regulating and/or processing element,in particular at least one comparator and/or by at least one amplifier,is provided: b) the, in particular first, input connection whereof isconnected to the second supply element, in particular to the secondcurrent source supported by a decoupling capacitor on the output side;c) the optional second input connection whereof is connected to at leastone optional reference voltage source or reference voltage source; andd) the output connection whereof is connected to the supporting supplyelement.
 11. A method for controlling at least one light-emittingcomponent, comprising: a) switching at least one switching element atleast between a first switching position and a second switchingposition, and the voltage supply is effected by use of at least onesupply element; and b) the light-emitting component is controlled byvarying its operating voltage.
 12. The method according to claim 11,wherein: a) the operating voltage of the light-emitting component isvaried by switching between the switching positions, of which at leastthe first switching position and the second switching position are oflow impedance for the operating frequency.
 13. The method according toclaim 11, wherein: a) the supply elements are each configured as avoltage source; and b) the light-emitting component is supplied: i) inthe first switching position with the entire or almost the entirevoltage provided by the first voltage source; and ii) in the secondswitching position with the entire or almost the entire voltage providedby the second voltage source.
 14. The method according to claim 11,wherein: a) the supply elements are configured as current sourcesconnected to one another in parallel, each supported by a decouplingcapacitor on the output side in particular by at least one decouplingcapacitor, which are connected to at least one supply voltage, inparticular to at least one voltage source, for example to at least onebattery.
 15. Use of the circuit according to claim 1 in: a) at leastone, in particular mobile, telecommunication system, for example in atleast one communication device, such as in at least one mobiletelephone; b) in at least one, in particular mobile, data communicationsystem or in at least one, in particular mobile, data processing device,for example in at least one handheld, in at least one notebook or in atleast one P[ersonal]D[igital]A[ssistant]; c) in at least one, inparticular mobile, data recording and/or reproducing device, for examplein at least one camcorder, in at least one digital camera or in at leastone H[igh]D[efinition]T[ele]V[ision]; or d) in at least onetransportation means, for example in at least one driver assistancesystem or in at least one navigation system of an automobile.